This invention relates generally to high voltage regulating systems and particularly to a low cost, high speed, regulating system for use with a conventional flyback transformer.
Flyback deflection systems are well known and widely used in television receivers. In such systems, a deflection voltage source drives an autotransformer with a ramp shaped current for deflecting an electron beam across the phosphor coated faceplate of a cathode ray tube (CRT). At the end of the ramp waveform, a relatively large retrace pulse is developed. This pulse is magnified by the turns of the flyback transformer winding and rectified to develop the high DC voltage required to operate the CRT. As is well known, although the high voltage system is tuned, the high DC voltage produced varies substantially with system loading that occurs due to increases in the electron beam current of the CRT. There have been numerous circuits in the art for "stiffening" the high voltage supply. In many applications, a separate, non-deflection-based high voltage system is used because of its tighter tolerance on regulation.
With the growing use of computer monitors, the need for precision CRT displays has increased. In these uses, high voltage regulation is critical and needs to be closely controlled to prevent unacceptable raster distortion and size changes. On the other hand, the needs of the marketplace are such that the cost of the monitor must be maintained as low as possible. These conflicting requirements pose a dilemma which the present invention solves.